This invention relates to a draw-out unit for electrical switchgear cabinets. More specifically, this invention relates to a locking arrangement for a circuit breaker draw-out unit.
The use of switchgears in electrical distribution systems is well known. The switchgear houses a plurality of draw-out units, with each draw-out unit housing one or more switching devices, such as motor controllers and circuit breakers, releasably interconnected to one or more busbars. Periodically, the draw-out units are removed from the switchgear to allow for maintenance of equipment. The switching devices within the draw-out units make electrical contact with the busbars through a plurality of clip connectors, which extend from the draw-out unit. Each clip connector is electrically connected to an electrical conductor for connection to the switching devices of the switchgear. As the draw-out unit is inserted into the switchgear, the busbar slides between the two contact arms, and the contact arms frictionally engage the busbar.
Draw-out mechanisms are known in the art for use with molded case circuit breakers. One such mechanism is described in U.S. Pat. No. 4,743,715 issued May 10, 1988. These mechanisms have discrete positions for testing, installing and removing the circuit breaker. The positions are CONNECT, DISCONNECT and TEST. In the CONNECT position the circuit breaker, can be closed, opened or tripped. In the DISCONNECT position the circuit breaker is in the trip position. The third position is TEST, wherein the circuit breaker is disconnected from the main circuit. In the TEST position the circuit breaker can be closed, opened or tripped in order to check internal and external accessories such as auxiliary switches, shunt trip and under voltage and secondary circuits.
It is frequently necessary to ensure that electrical equipment cannot be operated, for example while maintenance work is being carried out. It is essential to ensure that circuit breakers in a draw out mechanism are secured in the DISCONNECT position to avoid inadvertent operation that can lead to unplanned personnel exposure or equipment damage
In an exemplary embodiment of the present invention, a locking arrangement for use on a draw-out mechanism mounted on a circuit breaker within a switchgear cabinet includes a fixed side plate arranged for mounting within switchgear cabinet, a mobile side plate includes a pin extending threrefrom, the mobile side plate arranged to move the circuit breaker in cooperation therewith and an obstructor plate pivotally mounted to the fixed sideplate, the obstructor plate having a slot and a notch extending from the slot, the pin traversing the slot to allow the mobile side plate to move relative to the fixed side plate.
The above discussed and other features and advantages of the present invention will be appreciated and understood by those skilled in the art from the following detailed description and drawings.